I would say I didn't think Annabelle, the prequel, was particularly great. While I loved the idea of how Annabelle came to be possessed and utterly evil, I think the film was just a creepy doll film. It literally relied on the creepy doll for all of its...well, creepiness. Now while dolls in general are creepy and Annabelle exceptionally so (I mean seriously, who would even want an ordinary doll like that near them or their homes!?), it lacked everything that made The Conjuring so good (the Warrens also among them).
And then to make it worse, later on, the demon-thing appears and suddenly all the horror is gone. We just have a CGI crappy monster now, great job. Do people remember the scene with the two daughters trying to sleep in the first movie? With the covers getting pulled down, "Did you fart?" because of the smell, and peeking into the darkness behind the door? Holy shit, that scene was incredible. It was spine chilling, sublime and demonstrates just how damned well The Conjuring was done (found (some of) it here on youtube [https://www.youtube.com/watch?v=fEw9RBXwgcA]). Annabelle was an interesting idea, badly (or perhaps lazily) realised.
I also love that the sequel is set in London, where I'm from